This applies only to the Civitai training tool, as my problem did not replicate on a different platform.
I had a problem recently when attempting to upload a dataset. After editing my tags/captions, when I clicked "next" to advance to the following page, it just spun forever.
After much trial and error and support help from Civitai Jane, the trouble was caused by a Syntax Error in the Trigger word. The culprit was replacing a "t" with "+" in my trigger word. Which was "+MDJ5". I wasn't able to upload without error until I changed the trigger word field and all the instances in my captions to "MDJ5".
I asked Jane for a list of keyboard characters to avoid and Jane told me:
While there are special characters that can be used as part of the trigger word, ones that you should avoid include:
+ and =
/ and \
?, %, and &
' and "
<>, (), [], and {}
# and *
There might be a few others, but based on the tickets that we've received about trainings, I haven't seen any issues with using !, @, and $.